1. Field of the Invention
The present invention relates to a color filter array, and more particularly, to a color filter array capable of obtaining more effective die area.
2. Description of the Prior Art
With the trend toward digital age, the development of display technique and change of broadcasting method that adopts digital signals have made kinds of flat display such as liquid crystal display (LCD), field emission display (FED), organic light emitting diode (OLED), and plasma display panel (PDP) more preferable than conventional cathode ray tube (CRT).
Furthermore, since the micro-display is able to provide larger images than abovementioned displays are by optical method, the micro-display is more preferred on demand for displaying ultra large-sized images. The micro-display possesses another advantage of being easily applied in different displays such as LCD or OLED. For example, the micro-display applied in LCD is so-called micro LCD panel. The micro-display is divided into two categories: transmissive and reflective. The transmissive micro LCD panel is constructed on a glass substrate, and lights are transmitted through the display panel. The reflective micro LCD panel is constructed on a silicon substrate, therefore it is also known as liquid crystal on silicon display panel (LCoS) panel. The LCoS panel not only adopts the silicon wafer as the substrate but also replaces the thin film transistors (TFTs) with MOS transistors. Furthermore, the LCoS panel uses metal material serving as pixel electrode, thus light is reflected.
Both transmissive and reflective micro-displays need color filter array. Please refer to FIG. 1, which is a schematic drawing illustrating a conventional color filter array of a micro-display. As shown in FIG. 1, the color filter array 10 includes a plurality of color filters 12R, 12G, and 12B arranged in a rectangular matrix and positioned on a wafer 14, which is a glass wafer or a device wafer. No matter the rectangular color filter array 10 is positioned on the glass wafer or the device wafer, it is formed corresponding to a sub-pixel array formed on the device wafer. As shown in FIG. 1, the color filter array 10 is positioned in the center of a die 16. The dies 16 are separated from each other by a scribe line 18. And in the cutting process, the cutter is individualizing each die 16 along the scribe line 18 of the wafer 14.
Please still refer to FIG. 1. In the cutting process, internal stresses are unavoidably generated in the wafer 14, and thus cracks are formed. In order to protect the functional devices from the stresses, devices such as the sub-pixel units and the corresponding rectangular color filter array 10 are positioned in the center of the die 16. And as shown in FIG. 1 the sub-pixel units and the corresponding rectangular color filter array 10 are kept from the margins of the die 16 with a distance d1. More particularly, a metal line 20 is positioned in the die corner to mark the die corner rule and is kept from the corner apex 16a by a distance d2 in accordance with the topological layout rules (TLR). For instance, when size of the die 16 is larger than 100 square millimeters, the distance d2 between the metal line 20 and the corner apex 16a is about 340 micrometer (μm); when size of the die 16 is smaller than 100 square millimeters, the distance d2 between the metal line 20 and the corner apex 16a is about 125 μm. More important, the metal line 20 and both sides of the die corner have included angles of 45 degrees for further protecting the devices formed near the die corner. And four corner apexes 10a of the rectangular color filter array 10 are also separated from the metal line 20 by a distance d3 in accordance with the TLR, which is larger than 25 μm.
As shown in FIG. 1, according to the TLR, the metal line 20 has to be separated from the corner apex 16a by the distance d2, the metal line 20 and both sides of the die corner have the included angles of 45 degrees, and the corner apex 10a of the rectangular color filter array 10 has to be separated from the metal line 20 by the distance d3. Because the abovementioned limitation in accordance with the corner rule and its specific shape limitation of the rectangular color filter array 10, the distance d1 between the rectangular color filter array 10 and the margin of the die 16 is made larger than TLR. And thus size of the rectangular color filter array 10 and the corresponding sub-pixel array are reduced. In other words, the valuable space in the periphery of the die 16 is wasted. With the ever-present demands for high resolution and device size reduction, and progress in the semiconductor manufacturing method, the effective die area in one die is more valuable. Therefore, it is in need to provide a color filter array capable of obtaining more effective die area.